In general, rotary power tools are light-weight, handheld power tools capable of being equipped with a variety of tool accessories and attachments, such as cutting blades, sanding discs, grinding tools, and many others. These types of tools typically include a generally cylindrically-shaped main body that serves as an enclosure for an electric motor as well as a hand grip for the tool. The electric motor is operably coupled to a drive member that extends from the nose of the housing. The electric motor is configured to turn the drive member at relatively high rotational velocities. The drive member includes a tool holder that is configured to retain various accessory tools so they are driven to rotate along with the drive member.
Rotary power tools are often configured for variable speed operation. Slide switches have been used to provide variable speed control in rotary power tools. Typically, the slide switch is located near the cord end of the tool and is movable in a circumferential direction between a minimum and a maximum speed position. The slide switch has a switch lever that generally follows the curvature of the cylindrical configuration of the housing. While effective for variable speed control of the tool, multiple “swipes” of the dial are required to cover the entire speed range of the tool.
In addition, a separate power switch is often required for turning the tool on and off. These power switches are typically connected between the power source of the tool and the controller as well as the motor. As a result, there is typically a high current draw through the switch when the switch is turned on. A mechanical switch with contact points are typically required to handle this current.